This invention relates generally to injection molding and more particularly to side gated apparatus having a plurality of heated nozzles extending from a melt distribution manifold which can be actuated to a forward position to facilitate installation and removal of side gate seals adjacent the front end of each heated nozzle.
Side gating from heated nozzles seated in openings in a mold through hollow side gate seals to cavities surrounding each heated nozzle is well known. However, as seen in U.S. Pat. No. 4,981,431 to Schmidt which issued Jan. 1, 1991, previously the side gate seals were first mounted on a heated nozzle and the heated nozzle was then inserted into place in an opening in the mold. This arrangement has the disadvantage that the outer ends of the seals cannot extend outwardly past the inner surface of the opening in the mold. Consequently, the cavities must be located very close to the heated nozzle. While this is suitable for some configurations, it is not satisfactory for applications where space for an additional cooling conduit is required around each cavity.
U.S. Pat. No. 5,591,465 to Babin which issued Jan. 7, 1997 discloses side gated apparatus wherein the manifold and heated nozzles can be advanced to a forward position to facilitate installation of the side gate seals. However, this apparatus has the disadvantage that there is no provision to return the melt distribution manifold and heated nozzles to the forward position to facilitate removal of the side gate seals for cleaning or replacement after the apparatus has been operating for some time.
As seen in the applicant's U.S. Pat. No. 4,786,246 which issued Nov. 22, 1988, valve gated apparatus using pistons to reciprocate heated nozzles attached to a melt distribution manifold between a retracted open and forward closed positions is known. However, those heated nozzles must have forwardly extending tips to provide the valve gating and the movement of the heated nozzles is part of the operating cycle so there is no way it can be transposed into apparatus having the combination of side gate seals and provision for removing them for cleaning or replacement.